No you are not too old to do this but you have to make the decesion soon and go throw your training in very little time around 1 year to 18 months. And then teach for a while then when you are about 35 you could join the regional and probably fly with them for a while. But I would look into the corp. side as you will not have retire at 60 like the airlines.
Iain
PS Airlines normally hire till you are in your mid 40's or so.